<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <title>Document</title>
        <script src="./vue.js"></script>
    </head>
    <body>
        <div id="app">
            计数器:{{ num }}<br/>
            <!-- <button @click="num++">+</button>
            <button @click="num--">-</button> -->
            <button v-on:click="add">+</button>
            <button @click="sub">-</button>
        </div>
    </body>
    <script>
        let app = new Vue({
            el:"#app",
            data:{
                num:0
            },
            methods: {
                add:function(){
                    this.num++;
                },
                sub:function(){
                    this.num--;
                }
            }
        })
    </script>
</html>